材料期刊网

对某厂Q345特厚板粗轧过程中缺陷的压合条件，以二维刚-粘塑性有限元法进行了数值模拟。结果表明：在足够的压下率下，特厚板中矩形缺陷能够被压合，缺陷的尺寸及在厚度方向的位置对缺陷压合有很大影响；板坯表面的缺陷压合所需的临界压下率最大，t/8处所需的临界压下率最小，即表面处的缺陷最难压合，缺陷压合由难到易按所处位置依次为表面、t/2、t/4和t/8，将该厂特厚板轧制道次压下率提高到18%以上，将可有效避免成品中缺陷的出现；矩形缺陷的长高比λ越大，临界压下率越小，越易压合；当λ从小于1增大到大于1的过程中，临界压下率急剧减小，但当λ继续增大，临界压下率减小的趋势变得比较平缓；当λ<1时，呈双“Y”字型闭合；当λ≥1时，呈“Z”字型闭合。

The closing behavior of porosity in continuous casting steel slab during rough transverse rolling was investigated using FE-code, ANSYS/LS-DYNA. Process parameters of extra-heavy Q345 steel plate obtained from a Chinese iron and steel works were used as a reference. The slab of initial width 3500mm and thickness 320mm was rolled down to 140mm. The results indicate that rectangular porosity in extra-heavy plate can be closed with appropriate reduction. The size and location of porosity have evident influence on closing behavior. Surface porosity needs the largest critical reduction to close, and the critical reduction of porosity located at 1/8 thickness is lowest. It’s an effective method to avoid porosity by increasing pass reduction over 18% for extra-heavy plate rolling. The larger of λ(ratio of porosity length to height), the smaller of critical reduction needs for closing. When λ increases from less than 1 to more than 1, the critical reduction rapidly decreases, but it slightly decreases with λ further increasing. Porosity closing as double “Y-shape” with λ<1, and like a “Z-shape” when λ≥1.